If you run your own hardware, getting stuff shipped to a datacenter and installed is 2 to 4 weeks (and potentially much longer based on how efficient your pipeline is)
And even if you are building with microservices, most standard servers can handle dozens in a single machine at once. They are all mostly doing network calls with minimal compute. Even better actually if they are in the same host and the network doesn’t get involved.
If you want to, there are simple tools to hook a handful of them as a cluster and/or instantly spawn extra slightly costlier VMs in case of failure or a spike in usage, if a short outage is really a world-ending event, which it isn’t for almost every software system or business. These capabilities have not been exclusive to the major cloud providers for years.
Of course we are generalizing a lot by this point, I’d be happy to discuss specific cases.
I suspect that if you broke projects on AWS down by the numbers, the vast majority don't needed it.
There are other benefits to using AWS (and drawbacks) bit "easy scaling" isn't just premature optimisation because if you build something to do something it's never going to do that's not optimisation it's simply waste.
Not too different from how many other lines of business get their clients in the door.